chore: update dune to use dune-config

src/core/jbuild

@@ -4,6 +4,6 @@
    (public_name containers)
    (wrapped false)
    (flags (:standard -w +a-4-42-44-48-50-58-32-60@8 -safe-string -nolabels -open CCMonomorphic))
-   (ocamlopt_flags (:standard (:include ../flambda.flags)))
+   (ocamlopt_flags ((:include ../flambda.flags)))
    (libraries (result uchar containers.monomorphic))
   ))

src/jbuild

@@ -1,10 +1,12 @@
 
+(executable
+  ((name mkflags)
+   (libraries (dune.configurator))))
 
 (rule
   ((targets (flambda.flags))
-   (deps ((file mkflags.ml)))
    (fallback)
    (action
-     (run ocaml ./mkflags.ml))
+     (run ./mkflags.exe))
   ))
 

src/mkflags.ml

@@ -1,13 +1,19 @@
+
+module C = Configurator.V1
+
 let () =
-  let major, minor =
+  C.main ~name:"mkflags" (fun c ->
-    Scanf.sscanf Sys.ocaml_version "%u.%u"
+    let version = C.ocaml_config_var_exn c "version" in
-      (fun major minor -> major, minor)
+    let major, minor =
-  in
+      Scanf.sscanf version "%u.%u"
-  let after_4_3 = (major, minor) >= (4, 3) in
+        (fun major minor -> major, minor)
-  let flags_file = open_out "flambda.flags" in
+    in
-  if after_4_3 then (
+    let after_4_3 = (major, minor) >= (4, 3) in
-    output_string flags_file "(-O3 -unbox-closures -unbox-closures-factor 20 -color always)\n";
+    let sexp =
-  ) else (
+      if after_4_3 then (
-    output_string flags_file "()\n";
+        ["-O3"; "-unbox-closures"; "-unbox-closures-factor"; "20"; "-color"; "always"]
-  );
+      ) else (
-  close_out flags_file
+        []
+      ) in
+    C.Flags.write_sexp "flambda.flags" sexp
+  )